1. Field of the Invention
The present invention concerns a device for mutually locking the actuation of at least two power switches, with the position of a switching shaft of each power switch being supplied, via a mechanical transmission, to a mechanical evaluation apparatus, which releases or locks the actuation of the power switch.
2. Description of the Prior Art
A locking device of this type has been disclosed by German Patent 44 09 172 A1. The transmission means described therein are wire triggers or sheathed-wire Bowden controls, which may be of considerable length in some switching systems. Depending on the arrangement of the power switches to be mutually locked, it may also be necessary to arrange the flexible transmission means with a plurality of bends with different curvatures. It has been found that actuating the flexible transmission means consumes a surprisingly high amount of energy, although tests performed on the Bowden controls or wire triggers have found little friction.
It is also known that a system of tie rods can be used for mutually locking power stitches (German Patents 38 41 315 A1 and 44 09 172 A1). Also in these devices, it was found that actuation required considerable amounts of energy.